During an oocyte retrieval procedure, a relatively long aspiration cannula may be abdominally inserted into a patient so that the distal end of the cannula is in contact with a patient's ovary. The objective is to puncture an individual follicle on the ovary and withdraw oocytes through the needle. Generally, the proximal end of the cannula is connected to flexible tubing which is, in turn, connected through a test tube to a vacuum source. The vacuum source provides suction via the test tube to the needle to allow aspiration of the oocyte from the follicle. In some medical procedures to retrieve oocytes the physician may puncture several follicles in turn to extract oocytes from each without removal of the aspiration cannula from the patient.
Two different cannula styles are currently used for oocyte retrieval. One style is a single-lumen device. This style requires that any irrigation that is performed to assist with removal of oocytes is conducted through the same fluid path (or lumen) that is used for aspiration. In such instances, if an oocyte is lodged in the fluid path, the oocyte may be actually flushed back into the follicle during the irrigation procedure. Therefore, the use of a single-lumen device may create the potential of losing the oocyte during the irrigation procedure. Accordingly, some physicians prefer the use of a dual-lumen device for oocyte collection procedures. A dual-lumen device has a first fluid path, or lumen, for aspiration and a second fluid path for irrigation. The use of separate paths thereby reduces the possibility of flushing an oocyte out of the aspiration path during an irrigation procedure.
Oocytes are located in a fluid-filled sac or follicle. Before oocytes can be retrieved, a physician needs to be able to accurately puncture each sac prior to retrieval without damaging or losing an oocyte. In order to cleanly puncture the sac, all oocyte collection devices include a cannula having a sharpened bevelled tip. Ideally, the tip is gently inserted into the follicle to puncture the sac and release the oocytes.
It is useful that the physician knows the orientation and location of the tip of the cannula. Therefore, a need exists to provide a means for easily determining the orientation of the bevelled tip and to provide a means for allowing a physician to evenly rotate the tip.
It is an object of this invention to provide a solution to these problems or to at least provide a physician with a useful alternative
Throughout this specification the term distal is used to indicate that portion of the apparatus which in use is further away from the physician and the term proximal means the portion of the apparatus which in use is nearer to the physician.